1. Field of the Invention
The present invention is directed to an apparatus for processing a dead pixel, more specifically to an apparatus for detecting and compensating a dead pixel that can maintain excellent image quality by reducing image distortion and image deterioration.
2. Description of the Related Art
An image sensor has a two-dimensional arrangement of pixels, each of which converts light to an electrical signal according to the luminosity. By measuring the electrical signal, the intensity of light entered into each pixel can be inferred, and using this, images made up of pixels can be constructed.
An image sensor comprises pixel arrays, which consists of several hundred thousand to several million pixels, a device to convert analog data sensed from a pixel to digital data, and several hundred to several thousand storage devices. Due to the large number of devices, the image sensor is always exposed to a possibility of making an error in the process, and such an error can cause dead pixels, which become an important factor for determining the level and price of the image sensor. The pixel value resulted from a dead pixel is characterized by being exceedingly larger or smaller than the pixel values of neighboring pixels.
In the conventional method of processing a dead pixel, the data arranged in the horizontal direction are compared to detect and compensate the dead pixel. In reality, however, what is considered to be a dead pixel in the horizontal direction is often not a dead pixel in the vertical direction. For instance, as shown in FIG. 1, a complex image or a macro image may have a minute line in the vertical direction. This kind of minute line is expressed as data having a small number of pixels in the horizontal direction and has a completely different value. Thus, it is highly possible that this minute line is treated as dead pixel data. Therefore, if only the horizontal direction is considered for the compensation of dead pixel data, this kind of minute vertical line will be treated as dead pixels and converted to new values through an appropriate compensation method, thereby resulting in a serious distortion of the actual image.